Vibratory ball mills



' 2 Sheets-Sheet 1 Filed Oct. 5, 1951 INVENTOR.

Dec. 20, 1955 w. K. STONE 2,727,697

VIBRATORY BALL MILLS Filed Oct. 5, 1951 2 Sheets-Sheet 2 IN V EN TOR.

VIBRATORY BALL MILLS,

Walter K. Stone, Kensington, Md., n ssig nor to The United States ofAmerica as represented by the Secretary of Commerce 6 ApplicationOctober 5, 1951, Serial No. 250,007

7 Claims. c1L241--17s (Granted under Title 35, U. s. Code 1952 sec. 266)The invention described herein may be manufactured and used by or forthe Government of the United States for governmental purposes withoutthe payment to me of any royalty thereon in accordance with theprovisions of a the act of March 3, 1883, as amended (45 Stat. 467 35 U.s. c. 45 v The present invention is concerned with improvements invibratory ball mills of the type constructed by Dr. P. H. Hermans ofUtrecht, Holland. In this type of mill a mass of hard balls is containedin a jar which is revolved but not normally rotated. The inventionrelates more specifically to a means for also rotating the jarcontaining the balls so as to prevent settlement to the bottom of thejar of the material to be ground by the movement of the balls.

In vibratory ball mills of the general type with which the presentinvention is concernedthe settlement of the material to be ground to thebottom. of the jar in which the grinding takes place has alwayspresented a serious problem. In the original mill of this type it wasnecessary to periodically stop the mill, loosen the jar, rotate it,tighten it up and then start up the mill again. This, of course, is notpractical in a commercialoperation. Other attempts to overcome thisdifficulty have been only partially successful and usually require anumber of additional parts which greatly complicate the machine.

The primary object of the invention is to provide a vibratory ball millin which the jar is automatically rotated.

Another object of the invention is to provide for automatic rotation ofthe jar without the use of a number of extra parts.

Another object of the invention is to obtain automatic rotation of thejar as a result of a very simple modification of the prior art device.

Other uses and advantages of the invention will become apparent uponreference to the specification and drawings.

Figure 1 is a cross-sectional view taken along the length of themachine.

Figure 2 is a sectional view taken along line 2-2 of Figure 1.

Figure 3 is a view taken along line 3-3 of Figure 1 showing thearrangement between the weight and the shaft.

Referring to Figures 1 and 2, the vibratory ball mill is mounted on thebase plate 1. A motor 2 drives the shaft 3 through the flexible coupling4. The far end of of the shaft 3 is journaled in the bearings 6 and 7which are supported in the bearing housing 9. The bearings are keptproperly spaced by means of the spacer 8. The suspension yoke 11 isclamped about the bearing housing and is drawn tight by means of thebolt 12. One side of the yoke is extended vertically upward and thisvertical extension 13, together with the metal plate 14 form a jaw forclamping one end of the springs 16 and 17. The other ends of the springs16 and 17 are clamped in the clamps 18 and 19 respectively which are inturn rigidly mounted on the base 1. This assembly, including theflexible coupling 4, allows the shaft 3 and all parts mounted on it tofloat on the springs 16 and 17 for reasons to be explained subsequently.The bearing housing and all parts mounted on it are not rigidly securedto the bearings and therefore are allowed horizontal motion limited onlyby the travel limit sleeve 21 which is riveted to the bearing housing.However, this allowance for horizontal movement is not necessary, andthe bearing housing can be rigidly fastened to the bearings.

The free end of the shaft 3 is flattened on opposite sides so as toreceive the eccentric weight 22 as shown in Figure 3. The upper portionof the weight has teeth 23 which contact the teeth 24 on theweight-adjusting plate 26. This arrangement in conjunction with the slot40, in the weight 22, allows for adjustment of the weight with respectto the shaft 3.

The jar holder 27 is secured to theflange 25 of the weight housing 30 bymeans of the slip ring 28. The flange and the weight housing are merelya continuation of the piece forming the bearing housing 9. The outsidediameter and thickness. of the flange 29 of the jar holder 27 aredimensioned so as to provide sufficient clearance relative to the weighthousing 30 to permit rotation of the jar holder in the weight housing.The clearance between the horizontal face 31 of the jar holder and theface 35 of slip ring 28 determines the speed of rotation of the jarholder 27, for reasons to be explained below. Speeds from one to fourrevolutions per minute have been used.

A metal band 41 is clamped tightly about the jar 32 by means of theclamp 33. The band is then bolted to the jar holder 27 by means of thebolts 20.

The material to be ground and about 3700 small metal balls 39 which dothe grinding are put into the jar 32. The motor 2 drives the shaft 3 andthe eccentric weight 22 through the flexible coupling 4. Rotation of theweight about the axis of the shaft 3 and the restraining action of thesprings 16 and 17 cause the weight and the shaft 3 to move in a complexpath, which has a circular component, about the axis of revolution ofthe armature shaft 36 of the motor 2. The complex motion of the shaft 3is transmitted to the weight and bearing housings 30 and 9,respectively, through the ball bearings 6 and 7. This high speed motionof the weight and bearing housings and therefore of the jar holder 27and the jar 32 sets the balls in the jar into very rapid motion andcauses a minimum of 100,000 collisions per second between the balls.This permits materials to be ground to sizes of a few microns in lengthor less.

This much of the action of the mill is old and well known in the art.However, when the mill was operated as originally built, which was withthe jar holder bolted to the weight housing, the material being groundsettled to the bottom of the jar making it desirable to periodicallystop the mill, manually rotate the jar, and then start the mill upagain. This is obviously inconvenient.

In the device of the present invention the rotation of the jar isaccomplished by employing the principles of the standard internaldifferential gear. This is accomplished by the modification of the jarholder assembly. Formerly the jar holder was bolted to the weighthousing. However, in the present device, as previously pointed out, thejar holder is secured to the weight housing by means of the slip ring28. As a result of the internal differential gear action between thesurface 31 of the jar holder flange 29 and the surface 35 of the slipring 28, the circular component of the complex motion of the weighthousing is transmitted to the jar holder and the jar holder is made torotate in a direction opposite to the direction of rotation of theweight housing. The speed of rotation of the jar holder is dependentupon the relative diameters of the faces 31 and 35-and the speed ofrevolution of the weight housing.

It will be apparent that the embodiments shown are only exemplary andthat various modifications can be madeinconstructionand arrangementwithin the scope of my invention as defined in the appended claims.

I claim:

1. In a vibratory ball mill of the type comprising a container and-meansfor vibrating said-container including a shaft, means for rotating saidshaft from one end thereof, an eccentric weight on the other end of saidshaft. bearing means for supporting the last-mentioned end of saidshaft, a bearing housing-spring supported for relatively free movementthereof-anda holder for said container being supported'by said bearinghousing; the improvement comprising slip-ring means for providing aninternal differentialfriction gear coupling between said holder and saidbearing housing.

2. n a vibratory ball mill of the type comprising container and meansfor vibrating said-container including a shaft, means for rotating saidshaft from one end thereof, an eccentric weight on the other end of saidshaft, bearing means for supporting the last-mentioned end of saidshaft, a bearing housing spring supported for relatively free movementthereof, a holder for said container, said holder having acircularflange which is supported by said bearing housing; the improvementcomprising slip-ring means for providingan internal differentialfriction gear coupling between said flange and said bearing housing.

3. In a vibratory ball mill of the type comprising a container and meansfor vibrating said container including a shaft, means for rota-ting saidshaft from one end thereof, an eccentric weight on the other end of saidshaft, bearing means for supporting the last-mentioned end of saidshaft, a bearing housing spring supported for relatively free movementthereof and 'a holder for said container, said holder having a circularflange which is supported by said bearing housing; the improvementcomprising slip-ring means fastened to said bearing housing forproviding an internal differentialfriction gear coupling between saidflange and said bearing housing.

4. In a vibratory ball mill of the type comprising a container and meansfor vibrating said container including a shaft, means for rotating saidshaft from one end thereof, an eccentric weight on the other end of saidshaft,

bearing means for supporting the last-mentioned end of said shaft, abearing housing spring supported for relatively free movement thereofand a holder for said container, said holder having a circular flangewhich is supported by said bearing housing; the improvement comprising aslip ring having a circular groove, said slip ring being fastened tosaid bearing housing, the circular groove receivingsaid-circular flangeof-said holder, the diameter of the groove being larger than the outsidediameter of said flange.

5. In a vibratory ball mill of the type comprising a container and meansforvibrating said container including a shaft, means for rotating saidshaft from one end thereof, an eccentric weight on the-other end of saidshaft, bearing means for supporting the last mentioned end of saidshaft, a bearing housing spring supported for relatively free movementthereof and a holder for said container having a flange and beingsupported by said bearing housing; the improvement comprising slip-ringmeans on said bearing housingv engaging said holder flange for providingan internal differential friction gear coupling-between said holder andsaid housing.

6. in a vibratory ball mill of the type comprising a container and meansfor vibrating said container including ashaft, means for rotating saidshaft from one end thereof, an eccentricweight on the other end of saidshaft, bearing means for supporting the last mentioned end of saidshaft, a bearing housing having a flange spring supported for relativelyfree movement thereof and a holder for said container, said holderhaving acircular flange which is supportedby said bearing housing; theimprove ment comprising the combination of slip-ring means having afirst portion with a first internal diameter and a second portionwith asecond internal diameter, said holder flange having an outer, diametersmaller than the diameter ofthe secondjportion of said slip-ring means,and means for retaining said holder flange between the bearing housingflange and the first portion of said slipring means.

7. In a vibratory ballmill of the type comprising a container and meansfor vibrating said container including a shaft, means for rotating saidshaft from one end thereof, an eccentric weight on the other end of saidshaft, a bearing housing spring supported for relatively freemovementthereofand a holder for said container being supported by saidbearing housing; and means for rotating said container comprisinginternal differential friction gear coupling means between said bearinghousing and said container holder.

References Cited in the. file of this patent UNITED STATES PATENTS2,171,115 Kiesskalt Aug. 29, 1939 2,469,484 Thiman May 10, 1949 FOREIGNPATENTS 596,712 Great Britain Jan. 9, 1948

